Atwood heater

[stiles watson]

My Atwood Furnace is acting up. It was making a strange noise. When I opened the outside cover, the noise had stopped. However, I found a good bit of water inside from a blowing rainstorm. I ran the thermostat up and it came on fan, then the burner fired, flamed a few seconds and then shut down. Then the burner quit firing.

I noticed that what seems to be a circuit board at the top of the blower had a red blinking led light. It would blink 3 times and then pause and blink 3 times again.

Then it started blinking and at the same time, it seemed the blower would try to start. There was a lot of blinking and clicking. I finally pulled the connector to stop it.

In spite of my poor efforts at description, can any of you HVAC guys give me a clue?

[illapah]

Don't know if this is any help, I just did a quick internet search:

WIRING DIAGRAM FOR 2-STAGE FURNACE
DIAGNOSTIC CHART
A diagnostic LED is located inside the exterior access cover on the outside edge of the horizontal (2) stage control board. The following graph defines the codes.
2-Stage Furnace Diagnostics
An Excalibur 2-Stage furnace must use an Atwood Digital Thermostat.
1 Low Input voltage SOFT
2 Ignition Failure SOFT
3 Open High Limit SOFT
4 Stuck Sail Switch HARD
5
Module Fault HARD
Two Stage Furnace Models 1522 & 2334 WITH DOOR AND WITHOUT DOOR
MOT = Blower Motor SS = Sail Switch LS = Limit Switch PS = Power Switch
NOTE: A SOFT lockout is a condition that is timed and will make additional attempts to correct the problem. A HARD lockout requires reset of the thermostat or turning the power switch off then back on.

[EagleRunner]

Hi Styles,

Here is a Service Manual for the Atwood furnaces.

http://bryantrv.com/docs2/docs/hflamefurn04.pdf

On page 13 they provide a table that defines the furnace diagnostics for the flashing LEDs of the Two Stage Furnaces.

Hope this helps.

Tom

[Ozz]

I would cycle it 3 or 4 times, power it off, could be the wet conditions. Your safetys will keep everything safe.

[EagleRunner]

If you know the exact model of the Atwood furnace that is installed in your RV, you can go to this site and download the Service Manual PDF for yours.

http://www.atwoodmobile.com/heating-systems.asp

Good Luck.

Tom

[ole dude]

I agree, sounds as though dampness has caused the issue, as mentioned, may dry out with in a few cycles. Traces of moisture on the board my best guess.

[Ozz]

You could take one of those computer dusting cans of air, and blow it in the compartment on the board and igniter.

[stiles watson]

Thank you for your help. It saved me a service call. This morning I opened the cover again, daubed up the moisture I could see, and reconnected the circuit board. There were no LED lights flashing. Dianna ran up the thermostat and the furnace fired right up and stayed fired. I did print up the maintenance manual for the Excalibur 8500 series with a chart of diagnostic LED flash sequences.

Ozz, good idea about the air. I had determined to use a hair dryer to dry things out if it had not started up. Guess it was just damp and those safety features protected everything.

[Ozz]

Cool Beans!